FAQ Detail

WHAT IS THE CONVERSION FROM NGVD29 TO NAVD88?

Because of crustal motion in Louisiana, such a determination is impossible in the 21st century. Subsidence due to crustal motion is a fact in the entire Lower Mississippi Valley, and research has shown that NAVD88 elevations as far north as Memphis, Tennessee are now in error by at least 0.20 foot since the new datum was published in 1990.